Re: How Bad Is My Resonance?
* should read
"a total diff° greater than .......6°..... means the screen is resonating too high"
Apologies.
Thelaz ■
Re: How Bad Is My Resonance?
thelaz
That is kind of a strange way of measuring resonance - what if you send the test cards and so I could have a look at it.
Regards
Ziggy Gregory
ziggy.gregory@vibfem.com.au ■
Need To See Please
scan the test cards.....for stroke all around the machine you described and then I can comment better. TKS ■
Re: How Bad Is My Resonance?
Thanks George
I have sent the scan to your email address
george@assinck.com
Looking forward to your feedback
Regards ■
Re: How Bad Is My Resonance?
Sorry for late joining!
There could be the problem of setting in the unbalance masses or their weights.
If the problem is solved, please let us know the findings.
Thanks. ■
Re: How Bad Is My Resonance?
Originally Posted by thelaz
Recently had a new drive attached to my screen. (sloped linear vibrating)
Our target RPM was 930 RPM (NDTesting showed polar resonance at 1000RPM). However, after installation, the exciter was running at 947- due to electrical complicatons.
Stroke card measurements were taken at 6 locations (RHFeed, RHMiddle, RHDischarge, LHF, LHM and LHD) on both sides of the sideplates, to check angle of throw- as per supplier reccomendations.
Following the procedure, the sum of the difference in angles from both sides is calculated, and this determines the amount of resonance in the structure.
eg
RHF = 41°, LHF = 36° ... diff = 5°
RHM= 34°, LHM = 34° ... diff = 0°
RHD = 29, LHD = 33° ... diff = 4°
TOTAL diff = 9°
The supplier has suggested that a total diff° greater than 9° means the screen is resonating too high, and is likely to crack at some location.
However, mine has been running for 3 months without concern.
Can anyone comment on similar experience?
I would like to keep operating in this region, but feel uneasy.
Going to a new gearbox will be $$.
Any literature or reference would be highly appreciated.
Cheers
Thelaz
If u find literature or reference pls let me know... b'coz i want to design Vib. screen ■
Stroke Cards
Thee strokes.....actual images.....should look basically identical all around, which would indicate that the machine is in fact in a BALANCED CONDITION all around when shaking.
If wildly, DIFFERENT......THE vibrating screen would actually shake in an UNCONTROLLED, ERRATIC way....INDICATING unbalanced state.
If a circle throw unit.......EXAMPLE.....3/8" circle at 840rpm range.....you would be operating between 3.5 and 4 G's accelerating force.
If the screen is nominally in a balanced state while vibrating......it very well could be the structure that is not designed with enough safety factor in it.....and that translates into ERRACTIC VIBRATION of the screen on the structure. ■
How bad is my resonance?
Dear colleagues
Recently had a new drive attached to my screen. (sloped linear vibrating)
Our target RPM was 930 RPM (NDTesting showed polar resonance at 1000RPM). However, after installation, the exciter was running at 947- due to electrical complicatons.
Stroke card measurements were taken at 6 locations (RHFeed, RHMiddle, RHDischarge, LHF, LHM and LHD) on both sides of the sideplates, to check angle of throw- as per supplier reccomendations.
Following the procedure, the sum of the difference in angles from both sides is calculated, and this determines the amount of resonance in the structure.
eg
RHF = 41°, LHF = 36° ... diff = 5°
RHM= 34°, LHM = 34° ... diff = 0°
RHD = 29, LHD = 33° ... diff = 4°
TOTAL diff = 9°
The supplier has suggested that a total diff° greater than 9° means the screen is resonating too high, and is likely to crack at some location.
However, mine has been running for 3 months without concern.
Can anyone comment on similar experience?
I would like to keep operating in this region, but feel uneasy.
Going to a new gearbox will be $$.
Any literature or reference would be highly appreciated.
Cheers
Thelaz ■